U.S. patent number 4,117,300 [Application Number 05/784,789] was granted by the patent office on 1978-09-26 for redundant welding method for metal battery containers.
This patent grant is currently assigned to GTE Sylvania Incorporated. Invention is credited to Charles R. Ricards.
United States Patent |
4,117,300 |
Ricards |
September 26, 1978 |
Redundant welding method for metal battery containers
Abstract
Hermetic sealing of battery containers is accomplished in such
containers comprising metal bodies provided with flanges by first
mating the bodies so the flanges are coextensive, planar resistance
welding the bodies together through the flanges and subsequently
peripherally laser welding the edges of the flanges together to
effect a redundant weld and an hermetic seal.
Inventors: |
Ricards; Charles R. (Emporium,
PA) |
Assignee: |
GTE Sylvania Incorporated
(Stamford, CT)
|
Family
ID: |
25133545 |
Appl.
No.: |
05/784,789 |
Filed: |
April 5, 1977 |
Current U.S.
Class: |
219/121.64;
29/623.1; 429/72; 220/DIG.29; 429/171 |
Current CPC
Class: |
B23K
26/22 (20130101); H01M 50/174 (20210101); B23K
26/60 (20151001); B23K 11/3081 (20130101); B23K
2101/12 (20180801); Y10T 29/49108 (20150115); Y02E
60/10 (20130101); Y10S 220/29 (20130101) |
Current International
Class: |
B23K
26/22 (20060101); B23K 26/00 (20060101); B23K
11/30 (20060101); B23K 26/42 (20060101); H01M
2/02 (20060101); B23K 027/00 () |
Field of
Search: |
;219/121L,121LM,86,87,80,119,120,64,79 ;29/623.1,623.2,730,763
;228/58,60,901 ;429/173,171,72,57,184,163 ;220/DIG.29,81R
;53/285 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Albritton; C. L.
Assistant Examiner: Paschall; M.
Attorney, Agent or Firm: McNeill; William H.
Claims
What is claimed is:
1. In a method of providing an hermetic seal between metal bodies
each having a longitudinal axis and a flange transversely extending
from said longitudinal axis the steps comprising: mating said
flanged bodies with said flanges coextensive; planar resistance
welding said bodies together through said flanges; and subsequently
peripherally laser welding the edges of said flanges together to
effect a separate, non-overlapping redundant weld and said hermetic
seal.
2. The method of claim 1 wherein said bodies and said flanges are
cylindrical and the welding electrodes employed in said resistance
welding are tubular.
3. The method of claim 2 wherein the inside dimension of at least
one of said electrodes is sufficiently large to accommodate a
protrusion formed on one of said bodies.
4. In a method of providing an hermetic seal between metal bodies
each having a longitudinal axis and a flange extending in a
direction transverse to said longitudinal axis, one of said flanges
being provided with a depending notch, the steps comprising: mating
said flanged bodies with said flanges coextensive;planar resistance
welding aid bodies together through said flanges in substantially
all areas except that including said depending notch, crimping said
notch shut; spot welding said crimp by beginning at the center
thereof an progressively working outwardly to the ends of said
crimp, each of said spot welds overlapping its neighbor; and
subsequently peripherally laser welding the edges of said flanges
to effect a redundant weld separate and distinct from said planar
resistance weld.
Description
BACKGROUND OF THE INVENTION
This invention relates to the formation of hermetic seals and more
particularly to a method for achieving hermetic seals between two
metallic portions of a battery container by employing redundant
welds.
Newer forms of batteries, both primary and secondary, develop high
voltages and high energy densities by employment of very reactive
materials such as lithium. Some even employ reactive cathode
electrolytes such as thionyl chloride. Packaging for such materials
must have a high degree of reliability since the materials are
dangerous and even toxic under many conditions. Accordingly,
hermeticity requirements have led to the use of metal cans for such
batteries, the cans being welded together. However, when such
batteries employ reactive and volatile ingredients like thionyl
chloride, simple welding is found to be ineffective. The high
pervasiveness of thionyl chloride allows it to leak through even
microscopic weld inadequecies.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to obviate the
disadvantages of the prior art.
It is another object of this invention to enhance the sealing of
batteries.
It is yet another object of this invention to provide increased
hermeticity in a novel welding system.
It is still another object of this invention to provide an hermetic
seal for containers which contain thionyl chloride.
These objects are accomplished in one aspect of the invention by
the provision of a welding method for bodies which have flanges
extending in a direction transverse to a longitudinal axis. The
flanges are mated together to be coextensive and a first planar
resistance weld is made therethrough. Subsequently, the edges of
the flanges are peripherally laser welded together forming a
redundant weld and hermetic seal with a high degree of
reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow diagram illustrating one embodiment of the
invention;
FIG. 2 is a flow diagram illustrating another embodiment of the
invention;
FIG. 3 is an exploded, elevational view of one type of battery case
which can be sealed by the method of the invention;
FIG. 4 is an elevational view of a step in the method with some
parts shown in phantom lines;
FIG. 5 is a perspective view of a welding electrode which can be
employed in one embodiment;
FIG. 6 is an elevational view of a container following a further
step in the method;
FIG. 7 is a diagrammatic elevational view of the sequence of spot
welding;
FIG. 8 is a diagrammatic plan view of the spot welding
sequence;
FIG. 9 is a diagrammatic elevational view of the laser edge
welding; and
FIG. 10 is an elevational view of a finished container.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
For a better understanding of the present invention together with
other and further objects, advantages and capabilities thereof,
reference is made to the following drawings and appended claims
taken in conjunction with the above-described drawings.
Referring now to the drawings with greater particularity, there is
shown in FIG. 1 a flow diagram of one embodiment of the invention
and in FIG. 2 a flow diagram of a second embodiment of the
invention. These flow diagrams are more easily understood with
reference to the article being worked upon; therefore, these
articles will first be described.
In FIG. 3 there is shown an article which can be an electrochemical
cell container 20. The container 20 is comprised of an upper metal
body 22 and a lower metal body 24 each having a longitudinal axis
25 and a flange 26 and 28 respectively, extending in a direction
transverse to the longitudinal axis. One of the metal bodies, e.g.,
22 can have a terminal pin 30 insulatingly sealed therein as by a
glass seal 32. Also, as is apparent from FIG. 3, one of the
flanges, e.g., 28 can be provided with a depending notch 34 which
provides communication with the interior of the container.
As noted above, the methods to be described herein have
applicability to a wide range of bodies to be sealed; however, they
are particularly applicable to hermetically sealed electrochemical
cells employing volatile, pervasive electrolytes.
To provide the sealed container 20, the upper body 22 and lower
body 24 are brought together with the flanges 26 and 28
co-extensive as is shown in FIG. 4. Resistance welding electrodes
36 and 38 are then brought into contact with the flanges and a
suitable welding current applied therebetween to effect a planar
resistance weld through the flanges. The electrodes 36 and 38 are
tubular and of a diameter such that only the flanges are contacted.
When one of the metal bodies, e.g., 24, is provided with a
depending filling notch 34, then the corresponding welding
electrode, in this case 38, is provided with a slot 40 or cut-out
portion so that no electrical contact is made therewith. The
perspective view of FIG. 5 illustrates such an electrode.
After the initial planar resistance weld is made the container 20
is filled with electrolyte by any suitable means and the filling
notch 34 is mechanically crimped shut as shown in FIG. 6. Since no
known form of mechanical crimping is sufficient to maintain a
pervasive electrolyte like thionyl chloride within the container,
it is necessary that crimped notch 34 be welded. This is
accomplished by the spot welding technique shown in FIGS. 7 and 8.
The spot welding begins at the center of the crimped area and then
progresses outwardly, alternating sides, to the previously welded
area. It is necessary that each spot weld overlap its previously
made adjacent weld. Proceeding in this fashion squeezes any
electrolyte trapped in the crimped area progressively outwardly
until the last weld is made; this last weld volatizing the
electrolyte and forcing it out of the seal area. In FIG. 8 the
first centrally located spot weld is indicated at 42, the remaining
welds being shown in phantom lines. The final welds 44 and 46
overlap the previously formed planar weld which extended to lines
48 and 50.
After the spot welding of the crimped notch 34 is completed the
edges of flanges 26 and 28 are peripherally laser welded as by a
laser 52, shown diagrammatically in FIG. 9. The depth of the laser
weld should preferably be between 0.003 inch and 0.010 inch to
insure a hermetic seal. In addition to providing the redundant weld
the laser operation rounds the edges of the flanges 26 and 28 to
present the appearance shown in FIG. 10.
The above sequence of operation is illustrated in the flow diagram
of FIG. 2.
The flow diagram of FIG. 1 illustrates a sequence of operation
wherein a filling notch is not employed. For example, the filling
and sealing technique shown in U.S. Pat. Nos. 3,426,170 and
3,489,266, can be used, in which case the crimping and spot welding
are not needed.
It will be seen from the above that there is herein provided a new
and novel method of achieving hermeticity in metal battery
containers. The redundant welds, formed on two different surfaces,
provides leak protection from even pervasive electrolytes such as
thionyl chloride, allowing this material to be used in high energy
density electrochemical cells.
While there have been shown and described what are at present
considered to be the preferred embodiments of the invention, it
will be apparent to those skilled in the art that various changes
and modifications can be made herein without departing from the
scope of the invention as defined by the appended claims.
* * * * *